Introduction

• Diseases of the cerebellum lead to loss of the 'fine-tuning' of movements of the body and head.
• Cause: many causes including vascular, inflammatory/infectious, neoplastic, congenital malformations, and degenerative disorders, eg lysosomal storage diseases Storage disease.
• Signs: presents as truncal ataxia, hypermetria with preservation of strength, intention tremor of head, broad base stance, possibly decerebellate rigidity.
• Involvement of adjacent structures may complicate the clinical picture; may have vestibular signs if flocculo-nodular lobe affected.
• Diagnosis: signs.
• Prognosis: good to poor depending on etiology.

Pathogenesis

Etiology

Degenerative

• Abiotrophies (most are autosomal recessive diseases).
• Neuroaxonal dystrophies (probably autosomal recessive diseases).
• Demyelinating diseases.
• Storage diseases Storage disease (most are autosomal recessive diseases).
• Spongiform encephalopathies (probable autosomal recessive diseases).

Neoplastic

• Primary Brain: neoplasia.
• Metastatic.

Nutritional

• Thiamine deficiency.

Inflammatory

• Idiopathic cerebellitis (generalized tremor syndrome Idiopathic tremors of adult dogs ).
• Infectious, eg viral, protozoal, rickettsial and mycotic.
• Granulomatous meningoencephalitis Granulomatous meningoencephalomyelitis.
• Presumed immune-mediated cerebellar granuloprival degeneration in the Coton de Tulear breed Coton de Tulear.

Toxic

• Lead Lead toxicity.
• Hexachlorophene.
• Organophosphates Organophosphorus poisoning.
• Metronidazole Metronidazole.
• Plant toxins.
• 5-fluorouracil.

Vascular

• Infarction.
• Septic emboli.
• Hemorrhage.

Traumatic

• Head injury Brain: trauma.

Anomalous

• Chiari-like malformation Chiari-like malformation syringomyelia (CM/SM).
• Intracranial intra-arachnoid cyst Spine: arachnoid cyst.
• Cerebellar hypoplasia.
• Dermoid-epidermoid cyst.
• Dandy-Walker syndrome.

Predisposing factors

General

• Canine herpesvirus Canine herpesvirus.

Specific

• Presently unknown.

Pathophysiology

• Most degenerative disorders of the cerebellum are genetically transmitted (or suspected of being hereditary) and are characterized by premature aging with degeneration and death of various neuronal cell populations.
• This mechanism of premature degeneration of cerebellar cortical neurons is termed 'abiotrophy'.
• Abiotrophy is a process by which cells develop normally but later degenerate because of an intrinsic cellular defect necessary for continued life of the neuron.
• These disorders tend to be breed specific.

• The cerebellum is a reinforcing and coordinating organ that plays an important role in harmonising muscle contraction without actually initiating motor activity.
• Due to its close association with the brainstem vestibular nuclei, the cerebellum also plays a role in the maintenance of equilibrium.
• Cerebellar disease results in an inability to regulate the rate, range and force of a movement, ie dysmetria.
• Limb movements tend to be clumsy, faltering and jerky.
• Initiation of movement is delayed and often accompanied by tremors, ie 'intention' tremors. Infrequently observed signs include opisthotonos (lesions occurring in flocculonodular lobe or fastigial nuclear area of cerebellum).

Timecourse

• Clinical signs frequently occur in young animals, usually within a few weeks or months after birth. The clinical course is usually progressive (weeks or months).

Diagnosis

Treatment

Prevention

Outcomes